What to do when you can't get over a relationship? Depressed?

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It's been over 5 months.. This guy was my first and only love, only guy I've ever even kissed. We dated for a year and a half. I can't seem to get over him. I still even check his twitter to see what he's up to. I know it only makes things worst but I literally can't stop. A mutual friend between us said she asked him about me one day and he said he had moved on and is talking to someone else. Yet, on his twitter he said he doesn't want a relationship. I see him at school 4 days a week and it's extremely hard. I don't even know why I'd want him to come back..all though we had many good times he could be so mentally abusive..constantly changing his mind about wanting to be with me..and he didn't even break up with me. We had an argument over something dumb and he told me he hoenstly didn't care anymore. I tried talking with him at school and he literally told me to F off. We haven't spoke sense. Once he had sent a friend request to me cause I got a notification for it but it was deleted before I even had time to accept..this was in November. But it's now February and he hasn't showed any signs of wanting to talk to me or be with me. I'm thinking of seeing a therapist because I can't move on I need advice. I've tried being happy and it doesn't work everything reminds me of him
We're 19 by the way..in College not High school

[Siam]

A lot of time people don't realise that the thing that is keeping them in a relationship is not the partner but the company and presence of someone else. We are all social creatures and no matter what people say no-one should be alone or really wants to be alone, but that does not mean you should get hung up on a bad relationship and from what you've said you know that this relationship was bad.
I think if you realise that this break up doesn't mean you've lost something special but you've actually gained freedom from a relationship that could have damaged your self worth and even worst stopped you meeting someone else think about it you could be wasting your time with this guy when theres someone out there much better suited to you- and there will be the statistics alone (there 6 billion of us!) prove that
theres no cure for heart break- or any charity or research team looking to find one unfortunately but i think the best way to move forward is to let go of it completely- you tried it didn't work out and you come out of it feeling bad now move on theres nothing left for you with him, be with your friends meet new people and before you know it you won't even remember his twitter name
good luck and all the best